There is a large black letterbox to the left of my display ever since some motherboard issues. I've definitely had the problem before, and it randomly fixed. On a different PC. I can move the mouse past the right side of the screen
My 'monitor' is a clunky Magnavox 1280x768 ~19" LCD HDTV. I've unplugged and plugged back in the DVI-VGA adapter, and same with both ends of the VGA cable.
The weird thing is, it's definitely Windows XP's problem. The POST screen is correct, even the WinXP loading screen. But once the display blanks to go to the Welcome screen, there's the problem.
The nVidia Control Panel's CRT Move Position function won't fix it, the display just moves into the black area.